1. Field of the Invention
The present invention relates to a technology that may be adopted to prevent electromagnetic noise leak in an electronic camera having an image-capturing element that receives subject image light entering into the camera body via a taking lens and is mounted in the camera body via a holder that holds the image-capturing element.
2. Description of the Related Art
In recent years, mega-pixel electronic still cameras provided with an image-capturing element (hereafter referred to as a CCD) with more than a million pixels have been put into practical use. A CCD reads out voltages stored at the individual pixels in units of single lines in response to a read signal having a specific clock rate. As the clock rate achieves a higher frequency or as the level of the voltages read by the CCD rises, the level of electromagnetic noise generated at the CCD and/or its drive circuit increases.
In the prior art, a metal shield plate is provided between a CCD drive circuit board located at the rear surface of the CCD and the associated inside surface of the camera body to attenuate the electromagnetic noise generated at the CCD and/or the drive circuit so that the noise does not leak from the camera body to the outside.
However, in an electronic still camera mounted with a CCD having dimensions of 23.7 mm (height)×15.6 mm (width) with the number of its pixels exceeding 2,500,000, the level of electromagnetic noise leaking from the camera body cannot always be reduced to a specific level or lower simply by providing a shield plate between the CCD drive circuit board and the camera body, as in the prior art. In other words, in such a large scale CCD, a relatively high voltage is used to ensure that the signal waveform corresponding to each pixel does not become blunted during a read. This, combined with a higher frequency of the read clock achieved to support a large number of pixels, raises the level of the electromagnetic noise.